"If a man with inflammatory bowel disease has an elevated PSA, it may be an indicator of prostate cancer," said Kundu, an associate professor of urology at Northwestern University Feinberg School of Medicine in Chicago.

For the study, researchers looked at more than 1,000 men with inflammatory bowel disease and a "control group" of more than 9,300 men without the disease. The men were followed for 18 years.

Men with inflammatory bowel disease had higher PSA levels, and were four to five times more likely to develop prostate cancer than those in the control group, the investigators found.

The research doesn't show that IBD causes prostate cancer, however, only that the two are linked.

Kundu noted that many men with inflamed digestive tracts have elevated PSA levels. He said their doctors shouldn't dismiss those numbers as simply the result of inflammation.

"Many doctors think their PSA is elevated just because they have an inflammatory condition," Kundu said in a university news release.

For now, however, until more research is underway, "there is no data to guide how we should treat these men," he added.